Sassfras root beverages were made by Native Americans for culinary and medicinal purposes before the arrival of Europeans in North America, but European culinary techniques have been applied to making traditional sassafras-based beverages similar to root beer since the 16th and 17th centuries.
The tradition of brewing root beer is thought to have evolved out of small beer traditions that produced fermented drinks with very low alcohol content that were thought to be healthier to drink than possibly tainted local sources of drinking water and enhanced by the medicinal and nutritional qualities of the ingredients used. Druggists began marketing root beer for its medicinal qualities.
Pharmacist Chares Hires was the first to successfully market a commercial brand of root beer. Hires developed his root tea made from sassafras in 1875, debuted a commercial version of root beer at the Philadelphia Centennial Exposition in 1876, and began selling his extract. Hires was a teetotaler who wanted to call the beverage “root tea.” However, his desire to market the product to Pennsylvania coal miners caused him to call his product “root beer” instead. In 1886, Hires began to bottle a beverage made from his famous extract. By 1893, root beer was distributed widely across the U.S. Non-alcoholic versions of root beer became commercially successful, especially during Prohibition.
Not all traditional or commercial root beers were sassafras based. One of Hires’s early competitors was Barq’s, which began selling its sasparilla-based root beer in 1898 and was simply labeled as “Barq’s.” In 1919, Roy Allen opened his root beer stand in Lodi, California, which led to the development of A&W Root Beer. One of Allen’s innovations was that he served his homemade root beer in cold, frosty mugs. IBS Root Beer is another brand of commercially produced root beer that emerged during this time and is still well-known today.
Safrole, the aromatic oil found in sassafras roots and bark that gave traditional root beer its distinctive flavor, was banned by the FDA in 1960 for commercially mass-produced foods and drugs. Large doses of safrole produced liver damage in laboratory animals or various types of cancer. So while small does may have been used for medicinal purposes, apparently larger does are not good for you. (from Wikipedia)